I have these 12V peristaltic pumps connected with my Arduino Mega via a IRLB8721 MOSFET. I have a 1N5819 schottky diode and a 0.1nF ceramic capacitor parallel to each pump.
When I haven't connected the Arduino with ground, to the circuit, the pumps start running.
Also, when I have the Arduino connect but not loaded with a sketch that declares the pump pins, the MOSFET's get really hot (some times the pumps start at a slow rate).
There is nothing wrong when I have everything connected and the pump sketch loaded; everything works. But I'm wondering if this is normal behaviour, or that I might have done something wrong?
I'm a beginner with al this stuff, so that's why I'm checking...
